This invention relates to a color-converted image forming apparatus which enables an input image information to undergo the optimum color conversion up to a use's requirement by a relatively simple operation.
In recent years, in consequence of the advance of full-color output devices toward exaltation of performance, general users have come to hold increasingly exacting diverse demands on the images produced by the devices. In the field of the computer graphics, for example, various demands such as the demand for faithful reproduction on a hard copy of a color displayed on a monitor and the demand for reproduction of an original image in a color equivalent or superior to the color of the original image have been gaining in enthusiasm.
Various measures have been contemplated to date for the fulfillment of these demands. The technique disclosed in JP-A-01-166,669 is counted among these measures.
This technique comprises picking a multiplicity of picture elements as samples from an input image, subjecting the points of these samples to calorimetric analysis, deriving color-conversion matrixes from the results of the calorimetric analysis with the aid of the least squares method, storing in a device a multiplicity of color-conversion matrixes enough to produce colors desired by a user or as numerous color-conversion matrixes reflecting the characteristics of relevant input and output devices, and allowing the user to retrieve from the device a particular color-conversion matrix fit for a given occasion. The user is enabled to obtain a hard copy faithful to an image by selecting the fittest of the color-conversion matrixes stored in the device.
The technique which is disclosed in JP-A-04-51,670 is another example. This technique allows the masking coefficient which is required by a user in obtaining a hard copy faithful to an image to be determined by the solution of simultaneous equations based on representative colors designated on a test copy.
The conventional color-converted image forming apparatus of this class (refer to JP-A-01-166,669), however, are at a disadvantage in being incapable of producing hard copies which win the perfect satisfaction of all the users without fail because they are aimed at producing hard copies to be required in all likelihood by prospective users either by superposing color-conversion matrixes or consulting a lookup table having necessary color-conversion matrixes described in advance therein with respect to an input image.
Makers of color-converted image forming apparatuses, in preparing color-conversion matrixes, have no alternative but to adopt those of average magnitude so to speak in order that they may satisfy the majority of users to a certain extent. The degree of this satisfaction to be found in the apparatus loaded with a fixed collection of color-conversion matrixes, therefore, is different between users such as apparel makers who belong to fields possibly in need of special color-conversion matrixes and common users who are fully satisfied with ordinary color-conversion matrixes.
For the solution of this problem, the conventional techniques described above cause an output device to store as many color-conversion matrixes as possible or, where the output device has no sufficient capacity for the storage, cause such an external device as a host computer, for example, to store surplus color-conversion matrixes in such a manner as to be readily transferred to the output device. The collection of color-conversion matrixes so stored does not necessarily contain such color-conversion matrixes as are truly needed by users. Besides, the color-conversion matrixes thus stored pose the problem of setting users at difficulty in associating hard copies desired to be obtained with the color-conversion matrixes in storage.
For the solution of the problem just mentioned, the method which allows a conversion coefficient corresponding to a conversion being sought by a user to be determined by relying on the user to extract a test chart as an output, choose a number of colors out of the colors on the chromaticity coordinates in accordance with specific conditions, and solve simultaneous equations based on the colors so chosen and find a masking coefficient (refer to JP-A-04-51,670) has been proposed. This method, however, entails the inconvenience of compelling the user to designate on the test copy what is intended by the conversion under consideration. The method is indeed capable of producing a hard copy desired by the user and, nevertheless, is at a disadvantage in involving a complicated work for the acquisition of the masking coefficient.